Dynamic Thermal Evolution and Damage Failure in Plasma-Sprayed Thermal Barrier Coatings During a Burner Cycle Test: Roles of Intrinsic Cracks and Pore Defects

The intrinsic defects in thermal barrier coating (TBC) seriously affect its thermal insulation performance and service life. In this work, four typical TBC models are developed based on the same image to quantitatively compare the effects of defects on insulation and interface damage. The coupling behavior of thermally grown oxide (TGO) and gradient thermal cycling is considered. The propagation and evolution of intrinsic, pore edge, and interface cracks in the multi-defect model are explored. Results indicate that intrinsic cracks cause a temperature difference of up to 15 °C on the flat coating surfaces. Intrinsic defects have no effect on interface temperature. Compared to the defect-free model, intrinsic cracks result in a maximum increase of 70% in normal stress near the interface and a 48% increase in shear stress. The fully damaged area in the POR-CR model is 40% higher than that in the HOM model. Based on the POR-CR model, which is closer to the real microstructure, the merging methods of internal and interface cracks are summarized into six types. The relevant results can provide important data support for a comprehensive understanding of the failure mechanism of in-service coatings and accurate prediction of service life.